{
  "bibcode": "2009GCN..9235....1N",
  "body": "L. Nava (INAF-OAB/Univ.Insubria); D. Burlon (MPE-Garching);\nG. Ghirlanda (INAF-OAB); G. Ghisellini (INAF-OAB); M. Nardini (SISSA)\n\nWith the spectral parameters and fluence of GRB090423 as measured by  \nFermi (von Kienlin et al., GCN 9229)\nand given its redshift z=8.1 (Fernandez-Soto et al., GCN 9222), we  \nestimate the isotropic equivalent energy\nEiso = 1.03E53 and the isotropic equivalent peak luminosity Liso =  \n1.88E53 (the value of Eiso is consistent\nwith that obtained with the Swift spectral results given in Palmer et  \nal. GCN 9204).\n\nGiven the rest frame peak energy Ep= 746 keV, we show ( http://www.brera.inaf.it/utenti/ghirla/GRB/090423.html \n  )\nthat GRB090423 is consistent both with the Ep-Liso correlation  \n(Yonetoku et al. 2004) and with the Ep-Eiso\ncorrelation (Amati et al. 2002, Ghirlanda et al. 2008, Nava et al.  \n2008; see also GCN 9227).\n\nNoteworthly, GRB090423 is remarkably similar to GRB 080913 and GRB  \n071020 with respect to the Amati and\nYonetoku correlations. It is worth mentioning that these three GRBs  \nare long bursts according to their observed\nT90 (12 s, 8 s and 4 s respectively) although, given their  redshifts,  \nT90 ~ 1 sec in the rest frame.\n\nFinally, considering the collimation corrected Ep-Egamma correlation  \n(e.g. Ghirlanda et al. 2007), we estimate that a\njet break should occur in the afterglow light curve between ~22 and 54  \ndays (1 sigma consistency) or between ~10 and  130 days\n(3 sigma consistency) assuming a homogeneous circum-burst environment  \nwith standard parameters\n(see Nava et al. 2006, Ghirlanda et al. 2007). However, this break may  \nnot be observed in the\nX-ray which, given the typical steep-flat-steep decay already observed  \nfor this burst\n( http://www.swift.ac.uk/xrt_curves/00350184/ ), could likely be due  \nto another emission component (e.g. Ghisellini et al. 2009).\n\nThis message may be cited.",
  "circularId": 9235,
  "createdOn": 1240610264000,
  "email": "giancarlo.ghirlanda@brera.inaf.it",
  "subject": "GRB 090423: energetic, luminosity and jet break",
  "submitter": "Giancarlo Ghirlanda at INAF/Brera  <giancarlo.ghirlanda@brera.inaf.it>",
  "eventId": "GRB 090423"
}